Means For Plate Heat Exchanger

ABSTRACT

The invention relates to a heat exchanger comprising a means and a plate stack, which plate stack is composed of a number of mutually similar heat transfer plates ( 1 ), every second heat transfer plate ( 1 ) in the stack being rotated 180° in a plane parallel with a heat transfer surface ( 9 ) in said heat transfer plate ( 1 ). A number of contact points ( 16   a - d ) are situated round a first port region ( 12 ) in such a way that at least one contact point ( 16   b, c ) adjoins two contact points ( 16   a, c  and  16   b, d  respectively), said contact points ( 16   a - d ) being in principle at the same radial distance from the centre of said port region ( 12 ). The invention further relates also to said means comprising a number of protrusions whereby the means fits into a pattern in said heat transfer plate ( 1 ). The invention also relates to a plate heat exchanger ( 3 ) comprising a plate stack ( 2 ) and at least one means ( 25 ) of the invention.

FIELD OF THE INVENTION

The present invention relates to a means for a plate heat exchangeraccording to the preamble of claim 1. Furthermore, the present inventionrelates to a plate heat exchanger comprising the means of the invention.

BACKGROUND TO THE INVENTION

Japanese patent specification JP 2002-081883 describes a heat exchangercomprising heat transfer plates with similar heat transfer plates. Inthe ensuing text, the term “heat transfer plate” is synonymous with theterm “plate”. The plates exhibit a pattern of ridges and valleysextending diagonally across the heat transfer plate. Stacking to form aplate stack entails the plates being placed on one another in such a waythat the ridges and valleys of a plate are connected to the ridges andvalleys of an adjacent plate via contact points. The mutual orientationof the plates is such that there is mutual divergence of the extent ofthe ridges and valleys of adjacent plates upon their mutual abutment atsaid contact points. Mutually adjacent plates are connected via saidcontact points to form a permanently connected plate stack.

A problem of heat exchangers comprising plates configured according tosaid patent specification JP 2005-081883 is that the contact pointsround the port regions have a tendency to snap. The term “snap” meansthe permanent connection between two mutually adjacent plates parting ata contact point. Factors inter alia which influence the degree of riskof a contact point parting are the position of the contact point on theplate and its proximity to other contact points. Round the port regionsin the embodiment according to patent specification JP 2005-081883, andon many conventional plates, contact points are provided round each portregion at different distances from the centre of the port region. Theresult is that the stresses acting at the respective contact pointsround the port differ because some of the contact points are situatedcloser to certain contact points than to other contact points. Contactpoints which are near to one another can thus distribute stresses amongthem, with the result that the respective contact points will be lessaffected by said stresses. This means that certain other contact pointswhich are situated round the port regions and are not close to anothercontact point will therefore have a greater tendency to part than othercontact points round the port regions.

A known technique for creating contact points round a port is to press anumber of nibs in the region round the port. Said nibs are situated atthe same radial distance from the centre of the port. A disadvantage ofsuch an embodiment is that the respective nibs require a large surfaceto enable them to be pressed in the plate. This means that the plate'sheat transfer surface is reduced by the surface devoted to pressing saidnibs, with consequent reduction in the heat transfer via said plate.

SUMMARY OF THE INVENTION

The object of the present invention is to eliminate or at leastalleviate the above mentioned drawbacks of the prior art. This objecthas according to the invention been achieved by a means for a plate heatexchanger having the characterizing features of claim 1.

A further object of the present invention is that the means shouldabsorb stresses to which plates and the plate package are subject.

A further object of the present invention is that the configuration ofthe means should result in reduction of the risk of incorrect assemblybetween the means and the plate stack.

A further object of the present invention is that the means should seala number of the valleys on an adjacent plate in the plate stack so as toreduce the total amount of medium which is between the means and theplate during operation.

An advantage which is achieved with a means according to thecharacterising part of claim 1 is that the means can absorb loads fromthe plate package, thereby improving the heat exchanger's service lifeand fatigue performance as compared with what they would be if the meanswas omitted.

A further advantage which is achieved with a means according to thecharacterising part of claim 1 is that the configuration of the meansreduces the risk of incorrect assembly during the manufacturing process.This is because a number of protrusions from the means fit into theadjacent plate in the plate stack against which the means abuts.

A further advantage which is achieved with a means according to thecharacterising part of claim 11 is that the amount of medium whichduring operation of the heat exchanger is between the means and theoutermost plate in the plate stack is reduced, thereby reducing theamount of medium which is passive and does not contribute to heattransfer. The result is optimisation of total energy use in a system forthe heat exchanger.

Preferred embodiments of the means further have also the characteristicsindicated by subclaims 2-8.

According to an embodiment of the means according to the invention, themeans is a plate with a material thickness which is thicker than theheat transfer plate in the plate stack to which it is adjacent. Thisenables the plate to absorb loads which occur in the plate package andthereby prevent deformation of the plates in the plate package.

According to an embodiment of the means according to the invention, themeans is an end plate.

The expression “end plate” in this specification means a plate whichabuts against the first plate and/or the last plate in a plate package.This means that expressions such as pressure plate, frame plate, coverplate, adapter plate, reinforcing plate etc., adjacent to a first orlast plate in a plate package are synonymous in this specification withthe expression “end plate”.

According to an embodiment of the means according to the invention, theprotrusion fits into a valley in the pattern of the adjacent plate,which valley extends diagonally from one port region of the plate at onelong side to the corresponding other long side. The risk of incorrectfitting between the means and the plate package is thus reduced, sincepositioning the means incorrectly relative to said plate stack will bedetected immediately because the means and the plate package will thenslide or be loose relative to one another.

The means comprises a first surface and a second surface. The firstsurface faces away from the adjacent plate in the plate stack. Thesecond surface faces towards the adjacent plate in the plate stack. Themeans has an outer periphery which in principle corresponds to theperiphery of the plate in the plate stack. This means that upon abutmentbetween the means and said plate in the plate stack the means will inprinciple cover the whole of the plate's heat transfer surface withassociated port portions.

According to an embodiment of the means according to the invention, thesecond surface has a second protrusion which fits into the pattern ofthe adjacent plate. The fact that the means has a second protrusionmakes it possible for a further valley which communicates with the firstport region to be blocked off from flow of medium. The first port regioncommunicates with a number of valleys in which medium can flow. Blockingthem makes it possible to reduce the amount of medium which is betweenthe means and the adjacent plate during operation.

According to an embodiment of the means according to the invention, theprotrusion extends along the second surface of the means and is oblongin shape and longer than the width of the valley in which the protrusionis situated. The means will thus be fixed and prevented from rotatingrelative to the adjacent plate.

According to an embodiment of the means according to the invention, theprotrusions extend along the second surface of the means, are oblong inshape and longer than the width of the respective valley in which therespective protrusion is situated. The fact that there are at least twoprotrusions makes it impossible for the means to be fitted incorrectlyto the adjacent plate. Incorrect assembly would be obvious from the factthat the means and the plate would slide relative to one another and beloose.

According to an embodiment of the means according to the invention, theprotrusions fit into the valleys in the pattern of the adjacent heattransfer plate and prevent a medium from flowing in the thus blockedvalleys. As mentioned previously, the protrusions help to ensureprevention of flow in the valley where the protrusion is inserted,thereby reducing the amount of medium between the means and the platestack.

According to an embodiment of the means according to the invention, theprotrusions fix the means to the adjacent heat transfer plate so as toprevent mutual rotation and mutual sliding of the means and the heattransfer plate. With advantage, the protrusions are connected to thevalleys by soldering. Other connection methods such as welding,adhesive, friction and bonding are possible alternatives to saidsoldering.

According to an embodiment of the means according to the invention, themeans covers at least one of the adjacent heat transfer plate's portregions and heat transfer surface. As previously mentioned, the meansand the adjacent plate have similar peripheries. The result is that themeans covers in principle the whole plate surface on the adjacent platein the plate stack which faces away from the plate stack against whichthe means abuts.

A further object of the present invention is to create a heat exchangercomprising a permanently connected plate stack made up of stackedsimilar plates, with at least one end plate permanently connected to thefirst or the last plate in the plate stack so that the heat exchangerwill be pressure-resistant and fatigue-resistant.

A further object of the present invention is to create a heat exchangerwhich has low manufacturing costs as compared with a traditionalpermanently connected heat exchanger in which at least one of the endplates comprises a pressed pattern across large parts of the end plate.

The abovementioned and other objects are achieved according to theinvention by the heat exchanger described above having thecharacteristics indicated by claim 9.

An advantage which is achieved with a heat exchanger according to thecharacterising part of claim 9 is that since the means comprises only afew protrusions from an otherwise planar surface the heat exchanger iscost-effective to make. This is because the manufacturing process doesnot involve any complicated machine for executing the protrusions in themeans as compared with a traditional means exhibiting a pressed patternand hence requiring a complicated press tool.

BRIEF DESCRIPTION OF THE DRAWINGS

Preferred embodiments of the device according to the invention aredescribed below in more detail with reference to the attached schematicdrawings, which only depict the parts which are necessary forunderstanding the invention.

FIG. 1 depicts a heat exchanger with a means and a plate stack.

FIG. 2 depicts a heat transfer plate.

FIG. 3 depicts part of a pattern on a heat transfer plate.

FIG. 4 depicts a means for use on a heat exchanger.

DETAILED DESCRIPTION OF VARIOUS EMBODIMENTS OF THE INVENTION

FIG. 1 depicts a heat exchanger (3) comprising a plate stack (2) and atleast one means (25). The heat exchanger (3) is provided with a numberof inlet and outlet ports with port recesses (32-35) for a medium. Theplate stack (2) comprises a number of plates (1) permanently connectedto one another by a known connection method. Known connection methodsare, inter alia, soldering, welding, adhesive and bonding.

FIG. 2 depicts a plate (1) according to the invention. The plate (1)comprises first and second long sides (4 and 5), first and second shortsides (6 and 7), a heat transfer surface (8) with a pattern (9)comprising ridges (10 a-d) and valleys (11 a-e). A first corner portion(14) is formed at the connection between the first short side (6) andthe first long side (4). A second corner portion (15) is situated at theconnection between the first short side (6) and the second long side(5). A first port region (12) is situated in the first corner portion(14). A second port region (13) is formed in the second corner portion(15). A central axis (18) extends transversely across the plate (1)between and perpendicular to the two long sides (4 and 5). The centralaxis (18) divides the plate (1) into two equal halves. The halves aremirror images to one another in shape, pattern and contour. This meansthat the plate (1) comprises in all four corner portions, four portregions, etc. As the plate (1) is symmetrical about said central axis(18), this description refers only to said technical features pertainingto one half of the plate.

The plate (1) is stacked in a plate stack (2, see FIG. 1) with similarplates (1). Every second plate (1) in said plate stack (2) is rotated180° in a plane parallel with the heat transfer surface (8). Each plate(1) comprises an upper side and a lower side. All the plates (1) in theplate stack (2) are placed on one another with their respectiveundersides facing the same direction. Such stacking results in the topside of the pattern (9) of a first plate (1) abutting against thepattern (9) on the underside of a rotated similar second plate (1).

The first port region (12) communicates with a number of ridges (10 a-d)and valleys (11 a-e). The ridges (10 a-d) and valleys (11 a-e) on theplate (1) on the respective sides of the central axis (18) are all inprinciple parallel with one another.

A contact point (16 a-d) is formed on the end portion of each of therespective ridges (10 a-d) which are adjacent to the first port region(12). Said contact points (16 a-d) are in principle situated at the sameradial distance from the centre of the first port region (12). Thecontact points (16 a-d) follow the extent of a circular arc (17) roundthe port region (12). The centre of the circular arc (17) is within thearea of the first port region (12).

Stacking two mutually adjacent plates (1) in said plate stack (2, seeFIG. 1) will result in a first contact point (16 a) on a first plate (1)abutting against the underside of a first valley (11 a) on a rotatedsimilar second plate (1) placed on said first plate (1). Second, thirdand fourth contact points (16 b-d) will correspondingly abut against theunderside of a second valley (11 b) of the same plates (1) as in thecase of the first contact point (16 a) and the first valley (11 a).

A second ridge (10 b) is connected to a third ridge (10 c) by a firstconnection (24). The second valley (11 b) is adjacent to the secondridge (10 b), the third ridge (10 c), the first ridge (10 a) and thesecond port region (13). The second ridge (10 b) extends between saidfirst connection (24) and the first port region (12). The result is theformation of said second valley (11 b) which not only runs round part ofthe second port region (13) but is also adjacent to the heat transfersurface (8) of the plate (1). The second valley (11 b) follows initiallythe second ridge (10 b) from the first port region (12) to the firstconnection (24). At that connection (24) the valley (11 b) is compelledto change direction in order thereafter to follow the third ridge (10 c)to the second long side (5). The fact that the second valley (11 b) runsround part of the second port region (13) results in the formation onits underside of an elongate area round part of said second port region(13). Said region (13) connects to the second, third and fourth contactpoints (16 b-d). As a result of said first connection (24) the ridges(10 a-d) can be parallel with one another and said contact points can besituated on the ridges (10 b-d) at in principle the same radial distancefrom the centre of the first port region (12). This makes it possiblefor there to be uneven stressing at respective contact points (16 a-d)round the first port region (12).

FIG. 3 depicts part of a pattern (9) in a plate (1, see FIG. 2)according to the invention. For the sake of comprehension, FIG. 3depicts only one ridge (10) and one valley (11), whereas the plate (1)according to the invention comprises a number of ridges and valleys. InFIG. 3 the ridge (10) comprises a crest portion (21) and two sideportions (22 a, b). The respective side portions (22 a, b) are connectedto the crest portion (21). The valley (11) is connected to the crestportion (21) by the side portions (22 a, b). The crest portion (21) hasthe same extent as the ridge (10) and the valley (11). An arcuate edgeportion (23 a, b) which has the same extent as the ridge (10) connects,on its respective side of the crest portion (21), the respective sideportion (22 a, b) to said crest portion (21). A first centreline (30),which has the same extent as the ridge (10), is situated in and alongthe crest portion (21). A second centreline (31), which has the sameextent as the valley (11), is situated in and along the valley (11).

Each ridge (10) varies in width along its extent so that the smaller thewidth of the ridge (10) the smaller the width of the crest portion (21).The radius of the arcuate edge portion (23 a, b) varies correspondinglyso that the smaller the width of the crest portion (21) the smaller theradius. The width of the respective valley (11) varies along its extentin a similar manner to the ridge (10) and its crest portion (21).

The centrelines (30, 31) of each ridge (10) and valley (11) are parallelwith one another on their respective sides of the central axis (18, seeFIG. 2).

The fact that the ridges (10) and the valleys (11) vary in width andhence in volume per unit width makes it possible to lead a medium toparts of the heat-transmitting surface of the plate (1) which inconventional plates are difficult to cause the medium to act upon. Thefact that the volume per unit width is increased in the regions whichare difficult to cause the medium to act upon makes it possible toutilise a larger surface on a plate (1) for heat transfer.

FIG. 4 depicts a means (25). The means (25) has correspondingly the sameouter periphery as a plate (1, see FIG. 1) stacked on similar plates (1)in a plate stack (2). The means (25) comprises a first surface (26), asecond surface (27, not shown in the drawings) and port recesses(32-35). A first protrusion (28) and a second protrusion (29) arepressed in the first surface (26) on the respective sides of a secondcentral axis (36). The position of this second central axis (36)corresponds to the central axis (18) of a plate (1, see FIG. 2)according to the invention. The respective protrusions (28, 29) stickout from the second surface (27, not shown in the drawings).

The means (25) is placed on the first and/or the last plate (1) in theplate stack (2, see FIG. 1). The protrusions (28, 29) in the secondsurface (27, not shown in the drawings) are shaped to fit into thepattern (9, see FIG. 2) on an adjacent plate (1). Upon abutment betweenthe means (25) and the adjacent plate (1) the first protrusion (28) isinserted in the second valley (11 b) in the plate (1). The secondprotrusion (29) is inserted in the fifth valley (11 e). Both the secondvalley (11 b) and the fifth valley (11 e) communicate with the firstport region (12).

In a plate stack (2) according to the invention it is desirable to beable to reduce the amount of medium which accumulates during operationbetween the means (25) and the adjacent plate (1). The insertion of saidprotrusions (28, 29) in a number of the valleys (11 b, 11 e) whichcommunicate with the first port region (12) prevents flow of medium inthese valleys (11 b, 11 e) from said port region (12) to the second longside (5). The result is optimisation of the total heat transfer in theheat exchanger (3) in that medium which does not contribute to heattransfer is reduced.

The invention is not limited to the embodiment referred to but may bevaried and modified within the scopes of the claims set out below, ashas been partly described above.

1-9. (canceled)
 10. A means intended to be adjacent to a heat transferplate of a plate stack with permanently connected heat transfer platesfor a plate heat exchanger, which heat transfer plate comprises a firstlong side and an opposite second long side, a first short side and anopposite second short side, a heat transfer surface exhibiting a patternof ridges and valleys, first and second port regions, the first portregion being situated in a first corner portion formed at the meetingbetween the first long side and the first short side, the second portregion being situated in a second corner portion formed at the meetingbetween the second long side and the first short side, and the firstport region being connected to a number of ridges and valleys, whichridges and valleys have in principle an extent from the first portregion diagonally towards the second long side, wherein a number ofcontact points are situated on the ridges in direct proximity to thefirst port region, which contact points are so positioned that at leastone contact point adjoins two contact points, the contact points beingin principle at the same radial distance from the center of the firstport region, and wherein the heat transfer plate is a first or last heattransfer plate in a plate stack made up of the heat transfer plates,which adjacent means covers at least one of the port regions on the heattransfer plate and part of the latter's heat transfer surface, whereinthe means comprises a first surface and a second surface, the firstsurface facing away from the adjacent heat transfer plate and the secondsurface facing towards the adjacent heat transfer plate and having in itat least one first protrusion shaped to fit into a valley in the patternof the adjacent heat transfer plates, which valley extends diagonallyfrom one port region of the plate at one long side to the opposite otherlong side.
 11. A means according to claim 10, wherein the means is aplate with a material thickness thicker than the heat transfer plate inthe plate stack to which it is adjacent.
 12. A means according to claim10, wherein the second surface comprises a second protrusion which fitsinto the pattern of the adjacent heat transfer plate.
 13. A meansaccording to claim 12, wherein each protrusion extends along the secondsurface of the means, has an oblong length and is longer than the widthof the valley in which the protrusion is situated.
 14. A means accordingto claim 12, wherein the protrusions extend along the second surface ofthe means, have an oblong length and are longer than the width of therespective valley in which the respective protrusion is situated.
 15. Ameans according to claim 12, wherein the protrusions fit into thevalleys in the pattern of the adjacent heat transfer plate and prevent amedium from flowing in the blocked valleys.
 16. A means according toclaim 12, wherein the protrusions fix the means to the adjacent heattransfer plate so that the means and the heat transfer plate areprevented from mutual pivoting and mutual sliding.
 17. A means accordingto claim 10, wherein the means covers the heat transfer surface or atleast one of the port regions of the adjacent heat transfer plate.
 18. Aplate heat exchanger comprising a plate stack and at least one meansaccording to claim 10, the plate stack being made up of a number ofsimilar heat transfer plates and the means being adjacent to a first orlast heat transfer plate in the plate stack, wherein the means comprisesa first surface and a second surface, the first surface facing away fromthe adjacent heat transfer plate and the second surface facing towardsthe adjacent heat transfer plate and having in it at least one firstprotrusion shaped to fit into a pattern in the adjacent heat transferplate.
 19. A plate heat exchanger comprising a plate stack and at leastone means according to claim 11, the plate stack being made up of anumber of similar heat transfer plates and the means being adjacent to afirst or last heat transfer plate in the plate stack, wherein the meanscomprises a first surface and a second surface, the first surface facingaway from the adjacent heat transfer plate and the second surface facingtowards the adjacent heat transfer plate and having in it at least onefirst protrusion shaped to fit into a pattern in the adjacent heattransfer plate.
 20. A plate heat exchanger comprising a plate stack andat least one means according to claim 12, the plate stack being made upof a number of similar heat transfer plates and the means being adjacentto a first or last heat transfer plate in the plate stack, wherein themeans comprises a first surface and a second surface, the first surfacefacing away from the adjacent heat transfer plate and the second surfacefacing towards the adjacent heat transfer plate and having in it atleast one first protrusion shaped to fit into a pattern in the adjacentheat transfer plate.
 21. A plate heat exchanger comprising a plate stackand at least one means according to claim 13, the plate stack being madeup of a number of similar heat transfer plates and the means beingadjacent to a first or last heat transfer plate in the plate stack,wherein the means comprises a first surface and a second surface, thefirst surface facing away from the adjacent heat transfer plate and thesecond surface facing towards the adjacent heat transfer plate andhaving in it at least one first protrusion shaped to fit into a patternin the adjacent heat transfer plate.
 22. A plate heat exchangercomprising a plate stack and at least one means according to claim 14,the plate stack being made up of a number of similar heat transferplates and the means being adjacent to a first or last heat transferplate in the plate stack, wherein the means comprises a first surfaceand a second surface, the first surface facing away from the adjacentheat transfer plate and the second surface facing towards the adjacentheat transfer plate and having in it at least one first protrusionshaped to fit into a pattern in the adjacent heat transfer plate.
 23. Aplate heat exchanger comprising a plate stack and at least one meansaccording to claim 15, the plate stack being made up of a number ofsimilar heat transfer plates and the means being adjacent to a first orlast heat transfer plate in the plate stack, wherein the means comprisesa first surface and a second surface, the first surface facing away fromthe adjacent heat transfer plate and the second surface facing towardsthe adjacent heat transfer plate and having in it at least one firstprotrusion shaped to fit into a pattern in the adjacent heat transferplate.
 24. A plate heat exchanger comprising a plate stack and at leastone means according to claim 16, the plate stack being made up of anumber of similar heat transfer plates and the means being adjacent to afirst or last heat transfer plate in the plate stack, wherein the meanscomprises a first surface and a second surface, the first surface facingaway from the adjacent heat transfer plate and the second surface facingtowards the adjacent heat transfer plate and having in it at least onefirst protrusion shaped to fit into a pattern in the adjacent heattransfer plate.
 25. A plate heat exchanger comprising a plate stack andat least one means according to claim 17, the plate stack being made upof a number of similar heat transfer plates and the means being adjacentto a first or last heat transfer plate in the plate stack, wherein themeans comprises a first surface and a second surface, the first surfacefacing away from the adjacent heat transfer plate and the second surfacefacing towards the adjacent heat transfer plate and having in it atleast one first protrusion shaped to fit into a pattern in the adjacentheat transfer plate.